A register-maintaining drive mechanism for a rotary printing press is disclosed in EP 0 951 993 A1. A longitudinal elongation of the web to be imprinted is determined from web tension and from operating values of the drive mechanisms. Elongation is compensated for by adjusting the circumferential register at the cylinders, or the register rollers. A change in transverse elongation detected by use of a sensor for detecting the web width is fed back via a correcting value to the reference variable of the traction roller, which is regulated to web tension constancy.
A method for regulating the drive mechanisms of a printing press, directed toward producing a constant web elongation, is disclosed in U.S. Pat. No. 3,025,791. Here, the measurement of the web elongation takes place close to the first print unit by comparing the angular position of the print unit, and thereafter the position of a marker on the material to be imprinted. A change in the relative position causes a change in the tension of the web of material to be imprinted to be effected in the draw-in unit.
DE 92 16 978 U1 discloses a first regulating circuit, where a tension between a print unit and a traction roller is regulated by a first circuit to be constant. In a second regulating circuit, the angular position of the cutting cylinder is regulated via the drive mechanism of the cutting cylinder on the basis of a rotary position of the print unit and the cutting cylinder, as well as on the basis of an optical signal which processes the position of a marker.